In the field of video signals, digitalization of video signals has been aimed for actualizing diversification in information to be transmitted, improvements in quality of images reproduced from the video signal and so on. For example, there has been proposed the High Definition Television (HDTV) system which uses a digital video signal composed of digital word sequence data representing video signal information. The digital video signal under the HDTV system (hereinafter, referred to an HD digital video signal) is formed in accordance with, for example, one of a series of standards established by the Broadcasting Technology Association (BTA) in Japan so as to be in the form of Y and PB/PR signals or G, B and R signals. In the case of the Y and PB/PR signals, Y represents a luminance signal and PB/PR represent color difference signals. In the case of the G, B and R signals, G, B and R represent green, blue and red primary color signals, respectively.
The HD digital video signal produced in the form of Y and PB/PR signals (hereinafter, referred to an HD digital video signal of the Y and PB/PR type) is a digital television signal for interlaced scanning by which each frame picture is reproduced at a rate of 30 Hz or 30/1.001 Hz (hereinafter, the expression “30 Hz” includes both of 30 Hz and 30/1.001 Hz) with first and second field pictures. That is, the HD digital video signal of the Y and PB/PR type for interlaced scanning has a frame rate of 30 Hz.
This HD digital video signal of the Y and PB/PR type for interlaced scanning is formed, for example, in accordance with such data formats as shown in FIGS. 1A and 1B. The data formats shown in FIGS. 1A and 1B include a luminance signal data sequence (Y data sequence) as shown in FIG. 1A, which represents a luminance signal component of a video signal, and a color difference signal data sequence (PB/PR data sequence) as shown in FIG. 1B, which represents color difference signal components of the video signal. Each of data words constituting the Y data sequence or the PB/PR data sequence are composed of 10 bits. The word transmission rate of each of the Y data sequence and the PB/PR data sequence is selected to be, for example, 74.25 MBps. A part of the Y data sequence which includes a portion corresponding to a horizontal blanking period and parts of portions corresponding to a couple of video data periods appearing before and after the horizontal blanking period in a horizontal period of the Y data sequence is shown in FIG. 1A. Similarly, a part of the PB/PR data sequence which includes a portion corresponding to a horizontal blanking period and parts of portions corresponding to a couple of video data periods appearing before and after the horizontal blanking period in a horizontal period of the PB/PR data sequence is shown in FIG. 1B.
In the Y data sequence, time reference code data SAV (Start of Active Video) which are composed of four 10-bit words (3FF(Y), 000(Y), 000(Y), XYZ(Y): 3FF and 000 are hexadecimal numbers and (Y) indicates a word contained in the Y data sequence) are provided just before a portion corresponding to the video data period and another time reference code data EAV (End of Active Video) which are composed of four 10-bit words (3FF(Y), 000(Y), 000(Y), XYZ(Y)) are provided just after the portion corresponding to the video data period. Similarly, in the PB/PR data sequence, time reference code data SAV which are composed of four 10-bit words (3FF(C), 000(C), 000(C), XYZ(C): 3FF and 000 are hexadecimal numbers and (C) indicates a word contained in the PB/PR data sequence) are provided just before a portion corresponding to the video data period and another time reference code data EAV which are composed of four 10-bit words (3FF(C), 000(C), 000(C), XYZ(C)) are provided just after the portion corresponding to the video data period. The time reference code data EAV and SAV contained in the Y data sequence are provided in a portion corresponding to the horizontal blanking period of the Y data sequence and the time reference code data EAV and SAV contained in the PB/PR data sequence are provided in a portion corresponding to the horizontal blanking period of the PB/PR data sequence.
Initial three 10-bit words (3FF, 000, 000) of four 10-bit words (3FF, 000, 000, XYZ), each of which is shown with (Y) or (C), are used for establishing word synchronization or line synchronization and a last one 10-bit word (XYZ) of four 10-bit words (3FF, 000, 000, XYZ) is used for discriminating the first field from the second field in each frame or for discriminating the time reference code data EAV from the time reference code data SAV.
The HD digital video signal produced in the form of G, B and R signals (hereinafter, referred to an HD digital video signal of the G, B and R type) is also a digital television signal for interlaced scanning by which each frame picture is reproduced at a rate of 30 Hz with first and second field pictures. That is, the HD digital video signal of the G, B and R type for interlaced scanning has a frame rate of 30 Hz.
This HD digital video signal of the G, B and R type for interlaced scanning is formed, for example, in accordance with such data formats as shown in FIGS. 2A, 2B and 2C. The data formats shown in FIGS. 2A, 2B and 2C include a green primary color signal data sequence (G data sequence) as shown in FIG. 2A, which represents a green primary color signal component of a video signal, a blue primary color signal data sequence (B data sequence) as shown in FIG. 2B, which represents a blue primary color signal component of the video signal, and a red primary color signal data sequence (R data sequence) as shown in FIG. 2C, which represents a red primary color signal component of the video signal. Each of data words constituting the G data sequence, the B data sequence or the R data sequence is composed of 10 bits. The word transmission rate of each of the G data sequence, the B data sequence and the R data sequence is selected to be, for example, 74.25 MBps. A part of the G data sequence which includes a portion corresponding to a horizontal blanking period and parts of portions corresponding to a couple of video data periods appearing before and after the horizontal blanking period in a horizontal period of the G data sequence is shown in FIG. 2A. Similarly, a part of the B data sequence which includes a portion corresponding to a horizontal blanking period and parts of portions corresponding to a couple of video data periods appearing before and after the horizontal blanking period in a horizontal period of the B data sequence is shown in FIG. 2B and a part of the R data sequence which includes a portion corresponding to a horizontal blanking period and parts of portions corresponding to a couple of video data periods appearing before and after the horizontal blanking period in a horizontal period of the R data sequence is shown in FIG. 2C.
In each of the G data sequence, the B data sequence and the R data sequence, time reference code data SAV which are composed of four 10-bit words (3FF(G), 000(G), 000(G), XYZ(G): 3FF and 000 are hexadecimal numbers and (G) indicates a word contained in the G data sequence), time reference code data SAV which are composed of four 10-bit words (3FF(B), 000(B), 000(B), XYZ(B): 3FF and 000 are hexadecimal numbers and (B) indicates a word contained in the B data sequence) or time reference code data SAV which are composed of four 10-bit words (3FF(R), 000(R), 000(R), XYZ(R): 3FF and 000 are hexadecimal numbers and (R) indicates a word contained in the R data sequence) are provided just before a portion corresponding to the video data period, and another time reference code data EAV which are composed of four 10-bit words (3FF(G), 000(G), 000(G), XYZ(G)), another time reference code data EAV which are composed of four 10-bit words (3FF(B), 000(B), 000(B), XYZ(B)) or another time reference code data EAV which are composed of four 10-bit words (3FF(R), 000(R)., 000(R), XYZ(R)) are provided just after the portion corresponding to the video data period. The time reference code data EAV and SAV contained in each of the G data sequence, the B data sequence and the R data sequence are provided in a portion corresponding to the horizontal blanking period of each of the G data sequence, the B data sequence and the R data sequence.
Although, under the current HDTV system, the HD digital video signal of the Y and PB/PR type or the G, B and R type for interlaced scanning which has the frame rate of 30 Hz, as described above, is used for reproducing color pictures, there has been proposed, as an HDTV system for the next generation, another HDTV system in which an HD digital video signal of the Y and PB/PR type or the G, B and R type for sequential scanning by which each frame picture is reproduced at a rate of 60 Hz or 60/1.001 Hz (hereinafter, the expression “60 Hz” includes both of 60 Hz and 60/1.001 Hz) without first and second field pictures. That is, the HD digital video signal of the Y and PB/PR type or the G, B and R type for interlaced scanning has a frame rate of 60 Hz. This HD digital video signal of the Y and PB/PR type or the G, B and R type for sequential scanning which has the frame rate of 60 Hz is usually called a progressive HD digital video signal.
Digital data constituting the progressive HD digital video signal having the frame rate of 60 Hz have been standardized in data formats in accordance with SMPTE 247M which is one of a series of standards established by the Society of Motion Picture and Television Engineers (SMPTE) in the United States. In the data formats standardized in accordance with SMPTE 247M, 1920 active data samples per line, 1080 active lines per frame, the sampling frequency of 148.5 MHz or 148.5/1.001 MHz (hereinafter, the expression “148.5 MHz” includes both of 148.5 MHz and 148.5/1.001 MHz), 8 or 10 bits for one word and so on are predetermined in addition to the frame rate of 60 Hz. Then, parallel data interface is selected to be 8 bits×2=16 bits or 10 bits×2=20 bits for data of the Y and PB/PR type and 8 bits×3=24 bits or 10 bits×3=30 bits for data of the G, B and R type.
For such 8-bit or 10-bit digital data constituting the digital video signal as mentioned above, some forbidden codes which can not be used for representing any video signal information are predetermined. For example, the forbidden codes for 8-bit data are 00h and FFh (00 and FF are hexadecimal numbers and h indicates a hexadecimal number), that is, “0000 0000” and “1111 1111”, and the forbidden codes for 10-bit data are 000˜003h and 3FCh˜3FF (000, 003, 3FCh and 3FF are hexadecimal numbers and h indicates a hexadecimal number), that is, “00 0000 0000”˜“00 0000 0011” and “11 1111 1100”˜“11 1111 1111”.
Generally, in the case of the HD digital video signal of the Y and PB/PR type, the sampling frequency of each of the PB and PR data sequences is selected to be a half of the sampling frequency of the Y data sequence. Hereinafter, as occasion demands, a digital video signal of the Y and PB/PR type will be indicated as a digital video signal of the 4:2:2 type. On the other hands, in the case of the HD digital video signal of the G, B and R type, the respective sampling frequencies of the G, B and R data sequences are the same as one another. Hereinafter, as occasion demands, a digital video signal of the G, B and R type will be indicated as a digital video signal of the 4:4:4 type.
Apart from the HD digital video signal as described above, there has been also proposed a kind of progressive HD digital video signal which is aimed for reproducing moving pictures of a cinefilm at twenty-four frames per second with so improved quality as to be substantially equal to that of images reproduced by means of the HDTV system and so-called a D-Cinema signal. Although the D-Cinema signal is able to be obtained in the form of one of the progressive HD digital video signals, the frame rate of which is selected to be, for example, 24 Hz or 24/1.001 Hz (hereinafter, the expression “24 Hz” includes both of 24 Hz and 24/1.001 Hz) as mentioned above, the frame rate of the D-Cinema signal is selected to be not only 24 Hz but also a rate other than 24 Hz, for example, 25 Hz or 30 Hz.
Digital data constituting the digital video signal having the frame rate of 24 Hz, 25 Hz or 30 Hz have been standardized in data formats in accordance with SMPTE 247M. In such data formats standardized in accordance with SMPTE 247M, 1920 active data samples per line, 1080 active lines per frame, the sampling frequency of 74.25 MHz or 74.25/1.001 MHz (hereinafter, the expression “74.25 MHz” includes both of 74.25 MHz and 74.25/1.001 MHz), 8 or 10 bits for one word and so on are predetermined in addition to the frame rate of 24 Hz, 25 Hz or 30 Hz. Then, parallel data interface is selected to be 8 bits×2=16 bits or 10 bits×2=20 bits for data of the Y and PB/PR type and 8 bits×3=24 bits or 10 bits×3=30 bits for data of the G, B and R type.
There has been also proposed, in addition to the HD digital video signal and the D-Cinema signal aforementioned, another kind of progressive HD digital video signal for which the frame rate of 60 Hz, 720 active lines per frame and 1280 active data samples per line are predetermined. This digital video signal is called a 720P signal in this application.
Digital data constituting the 720P signal have been standardized in data formats in accordance with SMPTE 296M. In the data formats standardized in accordance with SMPTE 296M, 750 lines per frame, the sampling frequency of 74.25 MHz), 8 or 10 bits for one word and so on are predetermined in addition to the frame rate of 60 Hz, 720 active lines per frame and 1280 active data samples per line. Then, parallel data interface is selected to be 8 bits×2=16 bits or 10 bits×2=20 bits for data of the Y and PB/PR type and 8 bits×3=24 bits or 10 bits×3=30 bits for data of the G, B and R type.
The 720P signal was initially proposed in a period of transition from analog video signals to HD digital video signals to be predetermined to have 720 active lines per frame which correspond to two-thirds of those of the HD digital video signal and 1280 active data samples per line which also correspond to two-thirds of those of the HD digital video signal. Accordingly, the 720P signal is inferior in definition of images reproduced therefrom to the HD digital video signal but suitable for representing images moving quickly because of the frame rate of 60 Hz.
In relation to the various digital video signals as described above, there has been further proposed to use a predetermined key signal for combining a certain digital video signal with other video signals. The key signal represents opacity or transparency of related video signals and is recommended to be used in “SMPTE RECOMMENDED PRACTICE” RP 157-1995.
When the key signal is attached to a digital video signal of the 4:2:2 type, a key signal data sequence which is contained in digital data constituting the key signal is formed with a data format similar to the data format of a Y data sequence contained in the digital data constituting the digital video signal of the 4:2:2 type and handled in the same manner as the Y data sequence. When the key signal is attached to a digital video signal of the 4:4:4 type, a key signal data sequence which is contained in digital data constituting the key signal is formed with a data format similar to the data format of a G data sequence contained in the digital data constituting the digital video signal of the 4:4:4 type and handled in the same manner as the G data sequence.
Under such a condition, it has come to be desired to produce the digital date constituting the HD digital video signal, the D-Cinema signal or the 720P signal with a series of words each made of more than 10 bits, for example, 12, 14 or 16 bits, that is, a 12-, 14- or 16-bit word sequence. However, with the current standards for digital video signals which include SMPTE 247M and SMPTE 296M aforementioned, 12-, 14- and 16-bit word digital data have not been standardized but only 8- or 10-bit word digital data have been standardized. Consequently, it is feared that some problems in compatibility or generalization are brought about on 12-, 14- or 16-bit word digital date which are produced to constitute a digital video signal.
Further, there is another problem in transmission of the 12-, 14- or 16-bit word digital date which are produced to constitute the digital video signal, as follows. In general, when digital data constituting a digital video signal are subjected to transmission, the digital data are converted to serial data to be transmitted. For such serial transmission of the digital data constituting the digital video signal, although it has been standardized that 8- or 10-bit word digital data constituting a digital video signal of the 4:2:2 type are to be transmitted in accordance with HD SDI (High Definition Serial Digital Interface) provided by BTA S-004 which is one of the standards established by the BTA, there has not been any other standard for standardizing the serial transmission of the 12-, 14- or 16-bit word digital date constituting the digital video signal or digital date constituting a digital video signal of the 4:4:4 type.
For the present, any practical embodiment of transmission system which can cause the serial transmission of the 12-, 14- or 16-bit word digital date constituting the digital video signal to be appropriately subjected to serial transmission with use of existing circuit devices used for serial transmission of, for example, 10-bit word digital date constituting a digital video signal, has not been previously found. Further, any literature or thesis disclosing the transmission system which can cause the 12-, 14- or 16-bit word digital date constituting the digital video signal to be appropriately subjected to serial transmission in such a manner as mentioned above, has not been previously found also.
With regard to transmission of digital data of the 4:2:2 or 4:4:4 type, it is required sometimes to transmit the digital data of the 4:2:2 or 4:4:4 type together with a key signal data sequence related thereto. In such a case, it is desired in view of easiness in practice, reduction in cost and so on that the key signal data sequence is transmitted as an additional information data sequence annexed to the digital data of the 4:2:2 or 4:4:4 type and it is also desired similarly that the digital data of the 4:2:2 or 4:4:4 type accompanied with the key signal data sequence are converted into serial data to be transmitted with use of existing circuit devices used for the serial transmission, for example, 10-bit word digital date constituting the digital video signal. However, as aforementioned, under the present situation in which it has been merely standardized that the 8- or 10-bit word digital data constituting the digital video signal of the 4:2:2 type are to be transmitted in accordance with HD SDI, any practical embodiment of transmission system which can cause 10-, 12-, 14- or 16-bit word digital date constituting a digital video signal of the 4:2:2 or 4:4:4 type which are accompanied with a key signal data sequence as an additional information data sequence annexed to the digital date to be appropriately subjected to serial transmission with use of existing circuit devices used for serial transmission of, for example, 10-bit word digital data constituting a digital video signal, has not been previously found. Further, any literature or thesis disclosing the transmission system which can cause the 10-, 12-, 14- or 16-bit word digital date constituting the digital video signal of the 4:2:2 or 4:4:4 type to be appropriately subjected to serial transmission in such a manner as mentioned above, has not been previously found also.
Accordingly, it is an object of the present invention to provide a method of producing digital data, by which digital data constituting a digital video signal such as one of an HD digital video signal, a D-Cinema signal, a 720P signal and so on with a series of words each made of more than 10 bits can be produced to be compatible with previous 8- or 10-bit word digital data constituting the HD digital video signal.
Another object of the present invention is to provide a method of transmitting digital data which can cause digital data constituting a digital video signal such as one of an HD digital video signal, a D-Cinema signal, a 720P signal and so on with a series of words each made of more than 10 bits to be appropriately subjected to serial transmission with use of existing circuit devices used for serial transmission of 8- or 10-bit word digital data constituting a digital video signal, and an apparatus for transmitting digital data, on which the method of transmitting digital data can be carried out.
A further object of the present invention is to provide a method of transmitting digital data which can cause digital data constituting a digital video signal with a series of words each made of more than 10 bits and a key signal data sequence related to the digital data to be appropriately subjected to serial transmission in such a manner that the key signal data sequence are transmitted as an additional information data sequence annexed to the digital date with use of existing circuit devices used for serial transmission of, for example, 10-bit word digital data constituting a digital video signal, and an apparatus for transmitting digital data, on which the method of transmitting digital data can be carried out.